Secure communication in nowadays communication networks is becoming more and more important. For example, authority and organizations having security related duties, government agencies, services like police, fire departments and ambulances and others, generally referred to in this application as emergency services, require a reliable and a protected communication system, which provides secure communications for all members of this communication network. Such a communication network is for example known in Germany as BOS-network. This network provides authentication of its members and encryption means, so that the communication is protected from access by third parties. This network is based on the TETRA system, which is a professional mobile radio and 2-way transceiver, also known as walkie talkie or push-to-talk service, and was specifically designed for use by emergency services. Although TETRA is very suitable for voice communication, data rates are limited to approximately 10 Kbit/s. This makes it impossible to use TETRA to transfer huge amounts of data, which are required e.g. for providing multimedia information like pictures, videos or others, which can facilitate the work of the users of the BOS network. Attempts to increase data rates are being made with specification version two of the TETRA standard, but nevertheless data rates are still not sufficient for the afore-mentioned applications and use cases.
Secure communication networks like TETRA do not only provide authentication and encryption means for communication, but also provide a user structure based on user groups to control the access to the TETRA network. The user groups can be formed to enable simple and quick communication between all user group members. The group structure is typically a hierarchically organized group structure, e.g. with user groups for the different emergency services, which have each on top an officer in charge, who is responsible for a group of squad leaders, which are the heads of individual squads with the different individual persons. The group structure allows enabling a hierarchical communication, so that a communication within one group can be extended within the hierarchy to members of upper and/or lower hierarchy levels. In case of local emergency situations, e.g. a traffic accident, requiring cooperation of different emergency services, e.g. police, fire brigade and ambulance, user groups of the different emergency services can be enabled to inter-communicate with each other, particularly user groups which are located within a local area. Also data communication within the user groups can be provided upon requirements of the emergency situation, including access to a protected database, and to improve the coordination between the different services. For example local maps covering the emergency situation can be provided to involved user groups.
Apart from such secure communication networks, public communication networks are known, which usually provide an IP-based communication with very high data rates compared to the TETRA standard, even compared to TETRA version two. IP-based communication allows any kind of communication, e.g. VoIP, multimedia services, data communication or others. The public communication networks can be based on different communication standards, like GSM/GPRS, UMTS, LTE, WiMAX or wireless LAN (W-LAN). Nevertheless, these public communication networks are not suitable for secure communication from user to user. Even in networks providing authentication and encryption means, network keys are not under control of the users who require a secure communication and are therefore potentially accessible by third parties. Even when using special user keys for enabling point-to-point encryption between a user and a communication service or between two users, keys have to be transmitted via the public communication network prior to enabling encryption. Accordingly, these keys are therefore potentially accessible by third parties.
Emergency services sometimes are equipped with means for providing access to a protected communication service. This communication service is under control of the respective emergency service and therefore allows secure communication. E.g. the emergency service can provide a proper WLAN access point to be used of all members of the respective emergency service to provide locally in an area of an emergency situation a protected communication service with high bandwidth. Nevertheless, in emergency situations it can be required to share communication and/or information of a particular database with members of others emergency services to improve the coordination of the different emergency services and to resolve the emergency situation as quick as possible. This is almost impossible with such communication services under control of an individual emergency service.